1. Field of Invention
Apparatuses and methods consistent with the present invention relate to a method of electro-plating a semiconductor packages. More particularly, the present invention relates to a apparatus and method of electro-plating singulated semiconductor packages by moving conductive parts and the singulated packages relative to each other.
2. Description of the Related Art
One of the last steps in manufacturing certain types of semiconductor packages, such as QFN packages, is to plate the metal frame with a conductor, such as solder. One such conventional method is to electro-plate a metal, such as solder, to the frame. FIG. 1 is a schematic view of a conventional method of electro-plating a strip of semiconductor packages. The electro-plating apparatus includes a container 1 that is filled with a plating chemical 2, such as Methane Sulfonic acid. An electrical power source 3 is connected to an anode 3a and a cathode 3b. The anode 3a is electrically connected to an anode plate 4 that contains solder particles. The cathode 3b is electrically connected to a clipper and belt that is attached to the metal frame 6 of the semiconductor packages to be plated. The apparatus also includes a circulation pump and filter 7, which circulates the chemical in order to prevent chemical debris sediment.
When an electrical current is applied by the electrical power source through the anode 3a and cathode 3b to the anode plate 4 and metal frame 6, the solder particles on the anode plate move (as shown by item 8) through the plating chemical and become plated onto the metal frame (as shown by item 9).
FIG. 2 illustrates differences between the conventional strip of semiconductor packages and the strip of semiconductor packages that is used in an embodiment of the inventive method. FIG. 2A shows a portion of a metal strip frame 10 that contains rail bars 11, tie bars 12, terminals 13 and die attach pads 14. Each of the rail bars 11, tie bars 12, terminals 13 and die attach pads 14 are electrically connected. As a result, all of the metal surfaces can be plated by the conventional method.
FIG. 2b shows what happens with individual semiconductor packages are singulated, or separated from each other. Specifically, the rail bars are cut. After singulation, the tie bars 12, terminals 13 and die attach pads 14 of each of the singulated packages are no longer electrically connected to the tie bars 12, terminals 13 and die attach pads 14 of the other singulated packages. As a result, because electric current can no longer flow through all of the metal parts, the parts cannot be electro plated.
While the conventional method works well for semiconductors packages on a strip, when the semiconductor packages are singulated prior to electro-plating, a new method is necessary. The need to electro-plate individual packages may arise when not all of the packages on a strip are properly plated during the conventional method. Rather than scrapping the unplated packages, they can be separated from the strip and plated in a separate process.
There is therefore a need to provide apparatuses and methods that can electro plate semiconductor packages that have been singulated.